KEY ISSUE
ARC FLASH HAZARD AND ELECTRICAL CONTRACTING: PART 2 — RESOURCES FOR THE MANAGEMENT OF THE ARC FLASH HAZARD Mike Frain CEng FIET MCMI continues on from last month’s key issue feature by offering details on managing arc flash hazards. While part one addressed UK electrical safety legislation, part two directs readers to reliable information to help duty holders comply with that legislation.
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s discussed in part one, UK legislation is risk-based and non-prescriptive. It is unlikely that the HSE will create specific guidance like the American NFPA 70E Standard for Electrical Safety in the Workplace, and using NFPA 70E directly in the UK without proper adaptation is unwise. Risk control measures should align with UK law, focusing on prevention. The following documents and online tools can help manage this hazard.
Figure 2.1 The IET arc flash risk management fact file
(the risk). This is derived from system conditions such as the condition of the equipment, the quality of the installation, measures used to contain an arc during switching under normal and fault conditions, how well it has been maintained, and whether it is being operated in accordance with its original design. Importantly, it is also directly related to the task to be performed. • Take action to eliminate the hazard or, if this isn’t possible, control the risk. The document highlights the use of the 4P approach, mentioned previously, to eliminate or control the risk.
IET arc flash risk management fact file
The IET Engineering Safety Policy Panel, of which I was the Vice Chair, created a fact file in 2021 called Arc flash risk management (Figure 2.1). The arc flash working group consisted of senior electrical engineers including a HM Principal Specialist Inspector (Electrical Engineering) and the Professional Lead at the Office for Nuclear Regulation. The fact file is free and can be obtained from the IET via theiet.org/ impact-society/factfiles/engineering-safetyfactfiles/arc-flash-risk-management. The IET fact file provides a helpful appreciation of the principles of arc flash risk assessments. It seeks to set out the key principles of arc flash risk management using a risk-based approach. It is aimed at persons (duty holders) with responsibility for the management of safety in the control and implementation of work on electrical power equipment. The document describes an approach, based on a hierarchy of risk control measures. It adopts a holistic risk management methodology using the 4Ps of Predict, Prevent, Process and Protect to ensure that arc flash hazards are systematically identified, analysed, and prevented from causing harm. Removal of the hazard by working only on or near equipment that is made dead and suitably isolated should always be the first-choice risk reduction measure. However, other prevention measures are identified that fall into the categories of automatic disconnection of supply, equipment design and/or operational measures, that can be adopted individually or collectively to provide safety.
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Considerations for flame resistant personal protective equipment (PPE), as a risk control measure, should only be adopted as a last resort principle. The document provides an assessment process and there is also a commentary on recognised standards and test methods for PPE in Appendix 2. The fact file points out that when carrying out a risk assessment, as a minimum we must: • Identify what could cause injury (hazards). This is derived from system parameters such as voltage, fault level and electrical protection arrangements. • Decide how likely it is that someone could be harmed and how seriously
The 4P approach to arc flash risk assessment will ensure that the three steps above are fulfilled. That will be through a quantitative prediction of the hazard and then through prevention to eliminate or significantly minimise the risk. Process, policies and procedures are then used to further reduce the likelihood and finally, personal protection against residual risk if needed. The model in Figure 2.2 is used to describe how these steps can be implemented. The cycle matrix diagram shown illustrates how the important first step of Predict is used to calculate the severity of the arc hazard. This is followed by Prevent, in that we apply the principles of prevention and order the risk control measures in a hierarchy. The next step is Process, policies and procedures where we apply the building blocks of safe procedures, safe places and safe people. The final step is Protect, which looks at providing PPE as a last resort which, if the previous three steps have been correctly
Figure 2.2 Diagram illustrating the 4P approach to arc flash risk assessment
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30/06/2025 09:59